Wayne, a few things. Store bought milk although is good for drinking going toward the expiration date for making cheese it should be as fresh as possible as it tends to degrade quickly.
Next, CaCl is used because Pasteurization breaks down the calcium, homogenization has nothing to do with it. So unless you are using raw milk you should use CaCl.
Heating too quickly can destroy things in the milk.
As for cream top milk mine always has a plug at the top that is creamy and sort of dryish. That's normal. What I do is open the container and squeeze out aoubt half the container, so it's lighter, then shake the hell out of it to disperse the cream. Then once in the vat I use a braun stick blender and keeping below surface, or you'll have milk everywhere (don't ask how I know), I blend until 90% of the cream is disolved.